Please read the description/textbox first. This video will give a much better insight about the properties of the test oscillator/dipmeter that can work between 20 MC and 350 MC.
This (the) highest frequency that it can stray out (say 350 MC) is given via the harmonics of the oscillator, found and studied via the “Tiny Spectrum Analyzer”.
Go to my earlier video’s to find more about that Tiny SA. It is also on the www, you can find much more and reliable info via the website of that Tiny SA. How it works etc.
This video is only a VLOG, but shows more or less the properties of this (HF/VHF) oscillator, made with the BD 139 NPN transistor and a basic LED detector circuit that has to detect whether the oscillator oscillates or not.
Oscillation is set via the 22 K or 25 K bias potentiometer, sensitivity is set via the 500 K potentiometer. They both influence each other, though in a logical way (watch the video).
Schematics about the development of the tester are here:
First circuit:
Playing with an oscillator circuit on 107 MC (schematic)
https://youtu.be/SUXYCphn2EU
Second circuit (first test, schematic):
https://youtu.be/Reu72iLq034
Third circuit (dipmeter & test oscillator, definite circuit 25 july 2022, schematic showed again)
https://youtu.be/u7GNIsv1yEo
The circuit NOW (27 July 2022, 4th circuit) is here https://youtu.be/JSkuQTTajPs
ABOUT THIS VIDEO (27 JULY 2022):
The harmonics of the experimental (20 to 6 or perhaps even less windings) coils can go to 350 MC with that BD 139 transistor. So a useful basic circuit for radio experiments between 20 MC and 350 MC.
CORRECTIONS TO THE VIDEO:
1. On 1.11 in the video I say “the potentiometer is on 10 pF” (Pico Farad), but of course I mean the tuning capacitor (!) is set to 10 pF.
2. On 6.55 I say “110 MC” but of course that is “120 MC”
This video (27 July 2022) is a VLOG where I show how such a test oscillator works. You can connect all kinds of coils to it, say between 30 copper wire isolated windings (of whatever kind) and (like I showed) 6 windings of 2 mm diameter massive copper wire.
This is/was installation wire in the Netherlands (household 230V-50 Hertz), but it is generally used overall, this massive copper wire with a diameter of say 2 millimeters.
Oscillation is set with 2 potentiometers, bias (25 K or 22K) and sensitivity (500K).
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I keep all my YT videos constant actual, so the original video’s with the most recent information are always on YouTube. Search there, and avoid my circuits that are republished, re-arranged, re-edited on other websites, giving not probable re-wiring, etc. Some persons try to find gold via my circuits. I take distance from all these fake claims. I cannot help that these things happen. Upload 27 July 2022.